In-process charging of gate electrodes in insulated gate field effect transistors (IGFETs) can damage the gate dielectrics of the transistors. In the most common form of IGFET, the modern MOSFET (metal-oxide-semiconductor field-effect transistor), the gate electrode is formed from polysilicon. In a MOSFET, in-process charging commonly occurs during the etching of the MOSFET's polysilicon gate. Charging of a polysilicon gate can also occur during the processing of layers subsequent to the processing of the polysilicon gate when those subsequent layers are electrically connected to the polysilicon gate. These subsequent layers are typically contact layers, other polysilicon layers and metal layers.
In a MOSFET, the in-process charging of the gate causes large voltages and large electric fields to occur across the gate dielectric of the MOSFET. This gate dielectric is commonly silicon dioxide. Large electric fields across the gate dielectric can cause small tunneling currents to flow through the dielectric and the tunneling currents can leave charge trapped in the dielectric. This dielectric charge can alter the threshold voltage of the MOSFET and can also change other device characteristics. Electric fields can sometimes also be large enough to cause gate to substrate breakdown or, where a doped well resides in the substrate, gate to well breakdown. Gate dielectric charging and gate to substrate or gate to well breakdown can each result in product failure.
Thus, what is needed is a method and apparatus for charge dissipation protection which prevents a conductive or semiconductive material such as polysilicon from accumulating damaging levels of charge during semiconductor fabrication. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.